1. Field of the Invention
The present invention relates to a sliding ball type constant velocity joint for a vehicle, and more particularly, to a sliding ball type constant velocity joint for a vehicle, which can absorb idle vibration generated from the vehicle during idling by creating a clearance between an outer spherical surface of an inner race and an inner spherical surface of a cage.
2. Description of the Related Art
In general, a joint functions to transmit rotational power (torque) between two rotation shafts which meet each other at an angle. In the case of a propeller shaft having a small power transmission angle, a hook joint, a flexible joint, etc. are used, and in the case of the driving shaft of a front wheel drive vehicle having a large power transmission angle, a constant velocity joint is used.
Since the constant velocity joint can reliably transmit power at a constant velocity even when an angle between a driving shaft and a driven shaft is large, the constant velocity joint is mainly used for the axle shaft of an independent suspension type front wheel drive vehicle. When viewed from a shaft, a tripod type constant velocity joint is provided to one end of the shaft which faces an engine (the inboard-side end), and a fixed ball type joint is provided to the other end of the shaft which faces a tire (the outboard-side end).
FIG. 1 is a cross-sectional view illustrating a conventional constant velocity joint for a vehicle.
As shown in FIG. 1, the conventional constant velocity joint for a vehicle comprises a housing 2 which transmits rotational power of the engine (not shown) and is defined with track grooves on the inner surface thereof, a shaft 1 which receives the rotational power from the housing 2 and rotates, an outer race 2 which is installed at an end of the shaft 1 and having grooves formed therein, an inner race 3 installed in the outer race 2, a plurality of balls 4 for transmitting the rotational power of the outer race 2 to the inner race 3, and a cage 5 for supporting the balls 4.
The outer race 2 has a track groove 21 parallel with the center axis and a cylindrical inner diameter 22.
The inner race 3 has a track groove 31 parallel with a central axle and an outer spherical surface cylindrical inner diameter 32.
The cage 5 has an outer spherical surface 51 having a spherical portion and a linear portion and an inner spherical surface 52 having a spherical portion.
Hereafter, the operation of the conventional sliding ball type constant velocity joint for a vehicle constructed as mentioned above will be described.
As the rotational power outputted from an engine (not shown) is transmitted to the shaft 1 through a transmission (not shown) and then transmitted to the inner race 3 through the outer race 2 and the ball 4, so that then a wheel (not shown) is rotated.
The ball 4, which is restrained by a grinding surface 53 of the cage 5 and is also restrained between the track groove 21 of the outer race 2 and the track groove 31 of the inner race 3, transmits rotational torque. In this case, the inner spherical surface 51 of the cage 5 restrains the outer spherical surface 32 of the inner race 3, and the grinding surface 53 of the cage 5 restrains the ball 4, thereby enabling axial sliding and articulated joint movement. When the joint is articulated, the cage 5 and the balls 4 are positioned on a bisecting line of an operating angle, thereby enabling constant velocity movement.
Therefore, as the ball 4 slidably moves in the track groove 21 of the outer race 2, the joint is articulated to follow the displacement of the vehicle.
However, the conventional sliding ball type constant velocity joint is configured such that axial power transmitted to the axially moving inner race 3 is transmitted to the inner spherical surface 52 of the cage 5 through the outer spherical surface 32 of the inner race 3 to push the balls 4. That is to say, the inner race 3, the cage 5, and the balls 4 are subunits, which move in the same axial direction at the same time, may not absorb idle vibration generated from the vehicle during idling but may transmit the same to a vehicle body.